0,0
0,+1
+1,0 -> (-1,-1), (0,-1)
0,-1 -> (-1,0), (-1,+1), (0,-1)
0,-1 -> (-1,+1), (0,-1)
-1,0 -> (0,+1), (+1,+1), (+1,0)
-1,0
0,+1
0,+1
0,+1
+1,0
+1,0
+1,0
0,-1
0,-1
0,-1
0,0


1
2
3 (1,1): (-1,-1), (0,-1)
4 (1,0): (-1,0), (-1,+1), (0,-1)
5 (1,-1): (-1,+1), (0,-1)
6 (0,-1): (0,+1), (+1,+1), (+1,0)

 1: 1
 2: 1

 3: 1, 2        (1)
 4: 1, 2, 3
 5: 1, 4
 6: 1, 4, 5

 7: 1, 6        (5)
 8: 1, 6, 7
 9: 1, 2, 8
10: 2, 9
11: 2, 9, 10
12: 2, 3, 11

13: 3, 12       (9)
14: 3, 12, 13
15: 3, 4, 14
16: 4, 5, 15
17: 5, 16
18: 5, 16, 17
19: 5, 6, 18
20: 6, 7, 19

21: 7, 20       (13)
22: 7, 20, 21
23: 7, 8, 22
24: 8, 9, 23
25: 9, 10, 24
26: 10, 25
27: 10, 25, 26
